An Etymological Dictionary of the German Language/Annotated/Zitze
Zitze, feminine, ‘nipple, teat,’ from the equivalent late Middle High German (rare) zitze, feminine; compare the corresponding Low German titte, feminine, Dutch tet, feminine, Anglo-Saxon tit, masculine (plural tittas), English teat, Swiss tisse, ‘teat.’ The usual word for ‘teat’ in Old High German is tutta, tuta, feminine, tutto, tuto, masculine; Middle High German tutte, tute, feminine, tütal, neuter; compare Tüttel. In Romance occur the cognate words — Italian tetta, zizza, zezzolo, ‘teat,’ French tette, feminine, teton, tetin, masculine, ‘nipple,’ Spanish teta, as well as Italian tettare, Spanish tetar, French teter, ‘to suck’; the double forms with t and z imply that these words were borrowed from Teutonic.